The invention relates to a process for the production of a novel catalyst and to the hydrogenation of maleic anhydride in the liquid phase at an elevated pressure and temperature to produce .gamma.-butyrolactone employing said catalyst.
Catalysts of multifarious compositions are available for the hydrogenation of maleic anhydride to .gamma.-butyrolactone, Raney catalysts being the best known catalysts. However as taught by U.S. Pat. No. 2,772,292, Raney catalysts are highly pyrophoric and cannot be regenerated so that it has become increasingly the practice to use supported catalysts. The supported catalysts contain nickel as the catalytic component or cobalt in combination with a promoter, for example molybdenum or rhenium. While these supported catalysts are also pyrophoric, they can be stabilized by treatment with air diluted with carbon dioxide or a protective gas. The stabilizing treatment is, however, cumbersome and expensive. The supported catalysts have the additional disadvantage that their selectivity for .gamma.-butyrolactone is not as high as would be desirable such that C.sub.3 and C.sub.4 alcohols and acids and their products of esterification are formed as by-products. The high by-product formation results in a reduced yield of .gamma.-butyrolactone and the catalyst is irreversibly deactivated by the acids.
It is an object of the invention to provide a process for the hydrogenation of maleic anhydride to .gamma.-butyrolactone in the liquid phase in high yields.
Another object of this invention is to provide a process for converting maleic anhydride to .gamma.-butyrolactone in the presence of a novel selective and non-pyrophoric catalyst which does not require stabilization.
Yet another object of this invention is to provide a method for preparing a new catalyst useful in converting maleic ahydride to .gamma.-butyrolactone where the catalyst is readily regenerable.
Other objects and advantages will become apparent from a reading of the following detailed description and examples.